Mineral ID Chart
Metallic (Luster) Minerals, H=hardness, SC=Specific Gravity
Mineral
H
SG
Streak
Color
Form
Cleavage/Fracture
Diagnostic
properties
Pyrite FeS2
6-6.5
5
Dark grey
Cubes or octahedrons
Brittle. No cleavage
Magnetite
Fe3O4
Chalcopyrite
CuFeS2
Hematite
Fe2O3
6
5.2
Dark grey
Octahedrons
No cleavage
3.5-4
4.2
1.5-6
2.1-2.6
GreenishBlack
Red to
red-brown
Often massive,
tetragonal system
Thin tabular crystals
or shapeless masses.
Indistinct cleavage and
uneven Fracture
No cleavage
Galena PbS
2.5
7.6
Graphite C
1
2.1-2.3
Brass yellow; tarnishes
brown.
Silvery grey to black.
Tarnishes grey. Opaque.
Brass yellow and tarnishes
to peacock blue-purple
Silvery grey, black, or brick
red. Luster can be
nonmetallic.
Silvery grey. Tarnishes dull
grey.
Silver grey to black
Cubes and
octahedrons
Flakes, short
hexagonal prisms,
and masses.
Brittle. 3 good cleavage
planes (cubes).
1 excellent cleavage
plane.
Cubic form, brassy color,
and SG=5.
Attracted to a magnet.
SG=5.2. No cleavage.
Greenish-Black Streak,
peacock colors on brass
Red streak. Metallic +
nonmetallic.
Earthy red.
SG=8! Silver cubes (form
and cleavage).
Dark grey. H=1. Greasy.
Dark grey streak.
Grey to
dark grey
Dark-grey
Note: All the minerals above have a metallic luster. Massive means lacking a defined form.
Non-metallic minerals (listed in decreasing hardness) Review mineral formula to connect to family! H=Hardness; SG = specific gravity
Mineral
H
SG Streak
Color and/or
Luster
Form
Cleavage/Fracture
Diagnostic
properties
Corundum
Al2O3
9
4
White
Gray, blue, pink, brown.
Glassy or dull.
Translucent to opaque.
No cleavage
H=9. Barrel-shaped,
flat-end
hexagons.
3.54.3
White
Red, black, or brown; can
be yellow, green, pink.
Glassy. Translucent.
Hexagonal prisms
with striated, flat
ends. Barrel
shaped
Dodecahedrons
(12sided polygons)
Garnet
X3Y2(SiO4)3 where X and Y are
combinations of Ca, Mg, Fe, Al
7
No cleavage.
Brittle. Conchoidal
fracture.
7
3.33.4
White
Pale or dark olive green
to yellow or brown.
Glassy. Transparent.
Quartz SiO2
7
2.7
White
Colorless, white, or gray;
can occur in all colors.
Glassy and/or greasy.
Epidote
Ca2(Al,Fe)3Si3O12(OH)
6-7
3.33.6
White
Green (with yellow or
brown tinge). Translucent
to opaque. Glassy.
Dodecahedron form,
red (sometimes),
glassy, conchoidal
fracture, H=7.
Green, conchoidal
fracture, glassy, H=7.
Usually granular. Not
a hexagonal crystal.
Glassy, conchoidal
fracture, H=7. Hex.
prism with pointed
end.
H=7. Green. Striated
crystal faces. Massive
Olivine (Mg,Fe)2SiO4
Short prisms
(usually too small
to
see).
Massive; or
hexagonal prisms
that end in a
point.
Striated prisms,
or
massive.
Conchoidal
fracture.Brittle.
Conchoidal fracture.
One good, one poor
and rarely visible.
Mineral
H
SG Streak
Color and/or Luster
Form
Cleavage/Fracture
Diagnostic
properties
Kyanite
Al2SiO5
4-7
3.6
White
Patchy blue; can be green,
white, gray. Glassy,
pearly. Translucent.
Green (can be white to
pink as well). Glassy.
Opaque.
Bladed masses.
Flexible crystals,
bent or twisted
Long, thin
columnar
or needle-like
crystals.
One perfect
cleavage plane
parallel to blades.
Blue, flexible blades.
Amphibole family: Actinolite
Ca2(Mg,Fe)5Si8O22(OH)2
6
33.5
White,
green
Plagioclase Feldspar family:
Anorthite and Labradorite
CaAl2Si2O8 to Oligoclase and
Albite NaAlSi3O8
Potassium Feldspar family:
Orthoclase and Microcline
KAlSi3O8
6
2.62.8
White
6
2.52.6
White
Pyroxene family: Augite
Ca(Mg,Fe,Al)(Al,Si)O6
5.56
3.23.5
White,
pale grey
Green to black; opaque.
Short, 8-sided
prisms (if
visible).
2 good cleavage
planes at nearly
right angles.
Amphibole family: Hornblende
Ca(Mg,Fe)4Al(Si7Al)O22(OH) 2
5.5
33.3
Greygreen,
white
Dark green to black.
Opaque.
Long, perfect
prisms.
2 cleavages planes.
Angles: 60° and
120°. Brittle.
Splintery fracture.
Limonite
Goethite (FeO(OH)
FeO(OH)*nH20
Apatite
Ca5(PO4)3(F,Cl,OH)
Fluorite CaF2
45.5
2.74.3
Yellow
brown
Light brown to brown,
Dull earthy luster.
Amorphous, can
be psuedomorph
No cleavage
5
3.1
White
Color varied, vitreous
hexagonal
Conchoidal frac.
Softer than quartz
4
3.2
White
Color varied, vitreous
Octahedral
4 excellent cleavage
directions. Gives
crystal shape
triangular faces.
Brittle.
Fluorescent, 4
directions of
cleavage. Triangular
faces.
Colorless, white, gray, or
black; can have iridescent
play of color from within.
Translucent to opaque.
Pink. Or white, orange,
brown, gray, green.
Translucent to
opaque.
Tabular crystals
or
thin needles
Tabular crystals
Green, thin needles.
2 good planes.
Angles: 56° and
124°.
2 good cleavage
planes at nearly
right angles.
2 good cleavage
planes at nearly
right angles.
Twinning. 2
cleavages
at 90°.
H = 6.
Subparallel
exsolution
lamellae. 2 cleavages
at 90°. Pink or
white
color. H = 6. No
twinning
H=5.5. Dark green or
black. 2 cleavages at
90°. (Looks like
HB.)
H=5.5. Dark green or
black. 2 cleavages at
60°& 120°.
Splintery
fracture. Long
prisms.
Dull, earthy and
yellow streak.
Mineral
H
SG Streak
Color and/or Luster
Form
Cleavage/Fracture
Diagnostic
properties
Calcite CaCO3
3
2.7
White
Usually colorless, white,
or yellow, can be green,
brown, or pink. Glassy.
Opaque to transparent.
Rhombohedrons.
3 excellent cleavage
planes. Angles:
< 90° and > 90°.
2.73.1
Greybrown
Black, green-black,
brown-black. Transparent
to opaque.
Short tablets.
Like a tablet of
paper.
1 excellent cleavage
– splits easily into
thin, flexible sheets.
2-2.5
2.73
White
Serpentine
Mg6Si4O10(OH)8
2-5
2.22.6
White
Colorless, yellow, brown,
or red-brown.
Transparent to opaque.
Pale or dark green,
yellow, grey. Opaque.
Dull or silky.
Short tablets.
Like a tablet of
paper.
Smooth, rounded
masses.
1 excellent cleavage
– splits easily into
thin, flexible sheets
No cleavage.
Chlorite
(Mg,Fe)5(Al,Fe)2Si3O10(OH)8
2-2.5
2-3
White
Dark or bright green.
Opaque.
Halite NaCl
2.5
2.12.6
White
Gypsum
CaSO4*2(H20)
2
2.3
White
1 excellent cleavage
– splits easily into
thin sheets.
Brittle. 3 excellent
cleavage planes:
cubes.
1 good cleavage
plane.
Bauxite
gibbsite, Al(OH)3
Talc
Mg3Si4O10(OH)2
1-3
22.5
2.72.8
White
Colorless, white, yellow,
blue, brown, or red.
Glassy.
Colorless, white, or grey.
Translucent to
transparent.
white, gray, yellow, red, dull
to earthy luster
White, grey, pale green,
or brown. Opaque.
Greasy or silky luster.
Short tablets.
Like a tablet of
paper.
Cubes.
Bubbles in HCL.
Double refraction (2
images visible
through
clear sample).
Rhombs, 3 cleavage
planes (not 90°),
H=3.
1 flexible cleavage
plane (sheet), dark
colored; brown
streak.
1 flexible cleavage
plane (sheet), light
colored; white streak.
Mottled green color.
Smooth, curved
surfaces. No
cleavage.
H>2.
Green, nonflexible
sheets. Very small
flakes.
Salty taste. H=2.5.
Cubic form and
cleavage.
H=2. 1 cleavage
plane.
Translucent.
pisolitic structure,
color
Feels greasy or
soapy.
H=1. Opaque. Not
metallic.
Mica family: Biotite
K(Mg,Fe)3AlSi3O10(OH)2
2.5-3
Mica family: Muscovite
KAl3Si3O10(OH)2
1
White
Tabular, prisms,
blades, or
needles.
Pisolitic structure
Shapeless masses
(if no cleavage
visible) or
tabular.
No cleavage
1 poor cleavage
plane (may not be
visible).
Note: Striations and splintery fracture are very similar. They both look like ridges; you can feel the texture of both. Splintery fracture results from
breakage (similar to breaking wood and getting splinters); striations usually results from crystal growth. Twinning is more lines, less ridges. It
cannot be felt – only seen.